This application claims the benefit of the Korean Application No. P2001-0032522 filed on Jun. 11, 2001, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a laser, and more particularly, to a high powered laser, in which an array of micro-chip lasers is provided and a cooling system of the array is improved for enhancing an output.
2. Background of the Related Art
A laser beam is obtained by exciting a material containing atoms of a high energy level placed between two reflectors, to repeat reflection of light emitted by the excitation between the two reflectors enough to stimulate emission. The laser beam is a coherent monochromic light with characteristics like an electronic wave. Utilizing those characteristics, the laser beam is used in various fields, such as space communication, precision machining, medical treatment, and physical property study.
Depending on the materials that cause the stimulated emission, lasers are classified into gas lasers, solid state lasers, semiconductor lasers, dye lasers, and the like. FIG. 1 illustrates a related art DPSS (Diode Pumped Solid State) laser, schematically.
Referring to FIG. 1, the related art DPSS laser is provided with a laser diode array (LD array) 11 used as a pumping light source, a focusing optical system 12, a first reflector 13, a laser medium 14, a second reflector 15, and a nonlinear optical material 16.
The DPSS laser shoots the laser beam by directing a light from the laser diode array 11 to the laser medium 14 for pumping the light, and amplifying the pumped light. The DPSS laser provides high power considering its small size in comparison to an existing solid state, or liquid laser, of which application is increasing significantly.
Particularly, the laser with the laser medium 14 and the nonlinear material 16 joined together is called as a microchip laser, which is shown in FIGS. 2-3B.
Referring to FIG. 2, LD array 11 and focusing optical system 22 are shown. The microchip laser 20 has the laser medium 24 and the nonlinear material 26 joined together. A reflector 23 or 25 is coated on a surface of the laser medium 24 or the nonlinear material, to form a resonator 27.
The resonator 27 has a first reflector 23 and a second reflector 25 coated on opposite surfaces of the laser medium 24 as one form, and the first reflector 23 coated on a surface of the laser medium 24 and the second reflector 25 coated on a surface of the nonlinear material as the other form, which are best shown in FIGS. 3A-3B.
Operation of the related art microchip laser will be explained, briefly.
A light xcex0 from the laser diode array 21 is incident to, and pumped at, the laser medium 24, and emitted therefrom in a light of a particular wavelength xcex1. Then, the light xcex1 is amplified, and shoots as the light xcex1 goes back and forth repeatedly within the resonator 27. In this process, the light xcex1 is turned into a light with a wavelength xcex2 one half of a natural frequency by second harmonic generation of the nonlinear material 26.
The microchip laser has advantages in that a length thereof can be reduced since the laser medium 24 and the nonlinear material 26 are joined, and a size thereof can be made smaller since the resonator 27 is formed by coating the reflectors 23 and 25 on surfaces of the laser medium 24 and the nonlinear material 26.
In the meantime, a plurality of microchip lasers 20 may be arranged on more than one line to fabricate one laser for providing a high powered laser beam, of which temperature gradient is best shown in FIG. 4.
Referring to FIGS. 4A and 4B, xe2x80x98Axe2x80x99, xe2x80x98Bxe2x80x99, xe2x80x98Cxe2x80x99, and xe2x80x98Dxe2x80x99 regions represents regions of the same temperatures, wherein it can be noted that the temperature becomes lower as it goes the farther away from the pumping light focus part, and there is heat transfer between adjacent microchip lasers 20.
In this instance, a desired power may not be obtainable due to the heat transfer between the adjacent microchip lasers 20, or, when excessive, the shooting of the laser beam is not possible. That is, when the power of the laser diode array 21 is made higher for shooting a high powered laser beam, the laser medium 24 and the nonlinear material 26 cause a thermal lens effect in which a light is refracted by heat. Moreover, the heat transfer between adjacent microchip lasers 20 makes the thermal lens effect greater.
In summary, the microchip laser array has a disadvantage in that a power higher than a certain limit can not be provided due to the thermal lens effect even if a high powered pumping light is incident thereto.
Accordingly, the present invention is directed to a high powered laser that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a high powered laser, in which an array of micro-chip lasers is provided and a cooling system of the array is improved for enhancing an output.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the high powered laser includes a microchip laser array having an array of microchip laser beam shooting parts, and a heat transfer member of a material with a high thermal conductivity fitted between, and in contact with, the microchip laser beam shooting parts, for transferring heat from the microchip laser beam shooting parts to outside of the high powered laser.
The high powered laser further includes a cooling member fitted in contact with the heat transfer member for forcible cooling of the heat transferred to the heat transfer member by water or air.
In another aspect of the present invention, there is provided a high powered laser including a microchip laser array having an array of microchip laser beam shooting parts, a heat transfer member of a material with a high thermal conductivity fitted between, and in contact with, the microchip laser beam shooting parts, for transferring heat from the microchip laser beam shooting parts to outside of the high powered laser, a cooling member fitted in contact with the heat transfer member for forcible cooling of the heat transferred to the heat transfer member by water or air, and focusing means fitted to an output end of the microchip laser array for focusing lights from the microchip laser beam shooting parts into a single laser beam.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.